Binder for mineral wool products

ABSTRACT

Process for providing a binder for mineral fibers, comprising the steps of: mixing together under reactive conditions an amine and an anhydride whereby water is added thereto, once substantially all the anhydride is dissolved and/or reacted in the amine.

[0001] The invention relates to a process for providing a binder formineral fibers, i.e. man made vitreous fibers, for example glass, slagor stone wool, a binder obtainable via such a process, and a mineralwool product comprising such a binder.

[0002] Mineral wool products generally comprise mineral fibers bondedtogether by a cured thermoset polymeric material. One or more streams ofmolten glass, slag or stone wool are drawn into fibers and blown into aforming chamber where they are deposited as a web on to a travellingconveyer. The fibers, while airborne in the forming chamber and whilestill hot are sprayed with a binder. The coated fibrous web is thentransported from the chamber to a curing oven where heated air is blownthrough the mat to cure the binder and rigidly bond the mineral woolfibers together.

[0003] During the curing step when hot air is blown through the mat tocure the binder, a binder as disclosed in WO 99/36368 can be displacedwithin the mineral wool fibers, whereby a non-uniform distribution ofthe binder results, specifically wherein less binder is to be found atthe bottom of the mineral fiber blocks (i.e. the side of the block wherethe hot air is blown into the product) than in the top thereof.

[0004] Also during curing, a large amount of the resin may be lostleading to undesirably high emissions and a high binder loss.

[0005] An object of the present invention is to improve on thissituation.

[0006] According to a first aspect there is provided a process forproviding a binder for mineral fibers, comprising the steps of mixingtogether under reaction conditions, an amine and an anhydride, wherebywater is added thereto only after the anhydride has substantiallydissolved in and/or reacted with the amine, and the reaction is thusterminated.

[0007] A second anhydride is preferably added to the reaction mixturewhereby the water is preferably added to the reaction mixtureimmediately before or together with the second anhydride, or whensubstantially all of the second anhydride is dissolved in and/or reactedwith the mixture of the first anhydride and the amine.

[0008] Water is most preferably added to the reaction mixture in anamount to make this easily pumpable.

[0009] Low viscous resin binders for mineral wool are known, wherein theusual procedure is to mix diethanolamine with water before adding anyanhydride to minimize viscosity/stirring problems and to obtain thedesired water solubility. These resins however contain a high amount ofrest monomers, i.e. unreacted starting material, and have thedisadvantages of providing a low molecular weight binder which has along curing time. In order to overcome these extensive curing times, itis often necessary to use a high curing temperature with theaccompanying problem that the high curing temperature and long curingtime cause extensive evaporation of the binder and non-uniform binderdistribution.

[0010] A binder so obtained, yields a high binder loss, high emissionand curing problems.

[0011] By utilizing a process according to the present invention, abinder is provided for bonding mineral wool products, wherein the amountof rest monomers, i.e. unreacted start material is reduced, and having ahigher average molecular weight, whilst still maintaining watersolubility.

[0012] Furthermore, the inventors have shown that utilizing the processaccording to the present invention, the amount of emissions can bereduced, the binder yield can be raised, the curing time can beshortened, whilst the product quality can be improved.

[0013] It is theorized that the monomers also take part in the bindercross-linking reaction during curing, but if this amount is too high andthe curing time is too long, most of the monomers evaporate.

[0014] The inventors have shown that providing the binder without wateraddition from the start of the reaction, reduces the amount of unreactedmonomers and increases the curing speed yielding a binder having ahigher average molecular weight.

[0015] Furthermore, the inventors have shown that the binder loss duringcuring is less because of the presence of less unreacted monomers,whereby a rapid viscosity increase is provided due to the shorter curingtime and the higher initial Mw. This rapid viscosity increase makes itdifficult for the monomers to evaporate from the reaction mixtureinstead having time to react as a binder component and take part in thecross-linking reaction. Furthermore, due to the increased viscosity ofthe binder obtainable by the process of the present invention, there isless displacement of the binder in the mineral wool, when the binder hasbeen applied to the mineral wool and curing is taking place.

[0016] In an embodiment, the amine is heated firstly to a temperature ofat least 40, preferably at least 50 and most preferably to about 60° C.whereafter the first anhydride is added, and the reaction temperaturethen is raised to at least 70, preferably at least about 80 and mostpreferably to at least about 95° C. at which temperature the secondanhydride can be added to the reaction mixture when substantially allthe first anhydride has dissolved and/or reacted.

[0017] Alternatively increasing the reaction temperature from 90-95° C.to 100-200° C. gives a higher conversion of monomers to oligomers.

[0018] A preferred temperature range is 120-170° C., and most preferredis 130-150° C.

[0019] The temperature is at least 100°, often at least 120°, andpreferably about 130° C. It is normally below 200°, and preferably below170°, more preferably below about 150° C.

[0020] The average molecular weight of oligomers is increased when thereaction temperature is raised.

[0021] The evaporation loss of binder made of resin reacted at highertemperature is lower when cured.

[0022] A binder produced under these circumstances wherein water isadded when the first anhydride has reacted, together with the secondanhydride or at the end of the reaction, in an amount to make the bindereasily pumpable, enables a binder with an increased average molecularweight to be provided but still having a desired pumpability, viscosity,and water dilutability.

[0023] A resin according to the present invention but made with wateraddition from the start has more than 50% unreacted monomers ofdiethanolamine and polycarboxylic acids (anhydrides reacted with water),less than 15% amide of complete amide formation and an average molecularweight of about 400 and a maximum of about 600.

[0024] A resin made according to the process of the present inventionwith water addition at the end, together with a second anhydride, orjust before the second anhydride has been added, has less unreactedmonomers, especially the polycarboxylic acids, less than 30% comparedwith water addition from the start, a higher amount of amides, 15% ormore of complete amide formation, and an average molecular weight of500-900 and a maximum of about 2000.

[0025] The first and second anhydrides, and the amine are also describedin claims 7-11.

[0026] The reaction mixture used as a binder can also comprise anaccelerator, a resin additive, a corrosion inhibitor to curb the effecton pipes and the like, and/or a cross-linking agent as described inclaims 13-19.

[0027] Further characteristics of the process are to be found in claims20-28.

[0028] The inventors have shown that the aged strength of the bindermixture can be improved by the addition of silane.

[0029] The amount of silane in the resin reaction mixture is at least0.1%, often at least 0.2% and preferably at least about 1%. It isnormally below 5% and preferably below 3% and is often about 1.5%.

[0030] In order to improve the water solubility of the binder a basemight be added upto a pH of about 8, whereby a pH of between about 6-8is preferred, more preferred being a pH of about 7. The base can bemixed with a polyacrylic acid and added to the resin after the resinreaction is stopped by water addition. The base thus need first be addedafter the resin is prepared. The base may be mixed with a carboxylicacid group containing polymer before addition. Suitable bases could beNH₃, DEA, TEA, or alkali hydroxides.

[0031] It is found that addition of one or more cross-linking agentswith a carboxylic acid group containing polymer increases the curingspeed of the binder.

[0032] The first and second anhydrides are chosen to provide reactionproducts with a large number of unreacted polycarboxylic acid groups,which is preferable for water solubility. A most preferred binderconsists of 30% polymer of DEA (diethanolamine), THPA(tetrahydrophthalic anhydride) and TMA (trimellitic anhydride), 15% DEAmonomer, 10% THPA monomer reacted with water to diacid, 5% TMA monomerreacted with water to triacid and 40% water. In the polymer preferablyabout 50% of the reacted DEA has reacted to an amide and the other 50%of the reacted DEA has reacted to an ester.

[0033] Another preferred binder consists of about 40% or more polymer,(DEA, THPA, TMA), about 10% or less DEA monomer, about 10% or less THPAmonomer and TMA monomer reacted with water to diacid, triacidrespectively and 40% water.

[0034] The invention will now be further clarified by way of thefollowing examples and reference to table 1, wherein a plurality ofresin formulations is shown.

[0035] Resin formulations were made (see tables 1, 2 and 3).

[0036] Key to Abbreviations in Tables:

[0037] DEA—diethanolamine

[0038] GLA—glutaric anhydride

[0039] SCA—succinic anhydride

[0040] TMA—trimellitic anhydride

[0041] ADP—adipic acid

[0042] THPA—tetrahydrophthalic anhydride

[0043] Base—ammonia, amines or inorganic hydroxides

[0044] PAA—polyacrylic acid

[0045] Silan—amino silanes as par examplegamma-aminopropyltriethoxysilane (prehydrolysed VS 142 from Witco or nothydrolysed A 1100 from Witco or similar from other producers)

[0046] PTA—phthalic anhydride

[0047] TABLE 1 Water Rest Rest Rest Calculated Calculated FormulationMol ratio add. acid % amine % DEA % amide % ester % 1 DEA:THPA 1:1.4from 52 91 46  9 45 start 2 DEA:THPA 1:1.4 during 21 70 24 30 46reaction 3 DEA:THPA 1:1.4 at the 18 78 23 22 54 end 4 DEA:THPA:TMA1:1:0.4 from 73 90 66 10 24 start 5 DEA:THPA:TMA 1:0.8:0.6 from 70 91 64 9 27 start 6 DEA:THPA:TMA 1:0.9:0.3 before 31 82 50 18 32 TMA 7DEA:THPA:TMA 1:0.8:0.3 before 36 82 47 18 35 TMA 8 DEA:THPA:TMA1:0.6:0.3 before 26 85 63 15 23 TMA 9 DEA:THPA:TMA 1:0.6:0.3 with 40 7555 25 20 TMA 10 DEA:THPA:PTA 1:0.8:0.3 from 77 86 68 14 18 start 11DEA:THPA:PTA 1:0.6:0.8 from 80 87 68 13 19 start 12 DEA:THPA:PTA1:0.7:0.3 at the 17 68 43 32 26 end 13 DEA:THPA:PTA 1:0.7:0.3 at the 2864 42 36 25 end 14 DEA:GLA 1:1.4 at the 38 33 12 67 21 end 15 DEA:SCA1:1.4 at the  0 29 19 71 10 end 16 DEA:THPA:SCA 1:0.6:0.7 at the 16 5432 46 22 end

[0048] TABLE 2 Accelerator/ Silane Temp. Water Rest Rest Cal.Formulation Amine Anhydride crosslinkers Base (%) [° C.] Mole ratioadded acid DEA amide % 17 DEA THPA + phosphinic NH₄OH 0.4 1301.0:0.6:0.3 at 18 39 — TMA acid the end 18 DEA THPA + H₃PO₄ NH₄OH 0.4130 1.0:0.6:0.3 at 18 39 — TMA the end 19 DEA THPA + phosphinic NH₄OH0.4 130 1.0:0.6:0.3 at 18 39 — TMA acid + PAA the end 20 DEA THPA + PAANH₄OH 0.4 130 1.0:0.6:0.3 at 18 39 — TMA the end 21 DEA THPA +phosphinic NH₄OH 0.4 170 1:0.6:0.3 at 10 23 TMA acid the end Amountadded Remaining accelerator/ Delaminating strength Binder Binder Cal.Average crosslinker Curing time, strength after yield distributionFormulation ester % Mw in dry matter 250° C. [sec.] [kPa] ageing [kPa][%] [%] 17 — 600  3% 60 15.2 9.1 85 Top- bottom is OK 18 — 600  3% 68 85Top- bottom is OK 19 — 600  3% + 10% 25 83 Top- bottom is OK 20 — 60010% 28 11.2 4.5 84 Top- bottom is OK 21 not  3% measured

[0049] TABLE 3 Polycarb. Silane Temp. Mole Water Rest Rest RestFormulation Amine acid Anhydride Crosslinker Base [%] [° C.] ratio addedacid* amine DEA % 22 DEA ADP PTA + PAA DEA 0.2 130 — at — — THPA the end23 DEA ADP PTA + PAA DEA 0.2 130 — at — — THPA the end Remaining Curingstrength Cal. Cal Amount time, Delaminating after Binder Binder amideester Average added 250° C. strength ageing Yield distributionFormulation [%] [%] Mw crosslinker [sec.] [kPa] [kPa] [%] [%] [%] 22 — —600 20% 20 13.4 3.6 59 Less binder 28 in bottom than in top 23 — — 60020% 20 12.1 4.0 67 Less binder 35 in bottom than in top

[0050] Formulation 22 and 23 were Prepared as Follows:

[0051] Formulation 22

[0052] Resin:

[0053] 116 kg DEA was transferred to a 400 l reactor and heated to 60°C. whilst stirring.

[0054] 16.3 kg ADP was added, and the mixture heated and reacted at 130°C. for 60 minutes.

[0055] Thereafter cooled to 85° C. and 33.8 kg of THPA was added.Thereafter 82.5 kg PTA was added and the temperature raised to 130° C.for 120 minutes.

[0056] Subsequently the reaction mixture was cooled to 110° C. and 100kg water added.

[0057] The temperature stabilised at approx. 50° C. The mixture wasstirred for a further 15 minutes until homogenous.

[0058] The resin was cooled and transferred to a storage tank.

[0059] The resin solids content was determined as 62.2% at 200° C. Restmonomers: 39% of added DEA, 12% of added THPA, 25% of added PTA. Averagemolweight about 600.

[0060] The amount of rest monomers was determined by taking seperatesamples of the resin for each component. The samples were heated to 200°c. in order to remove all water, and then measured.

[0061] Before use 4% DEA and 25% solids Acumer 1510 calculated on resinsolids, 0.4% of sum solids silane and water to 25% solids content, wasadded.

[0062] Results of Trial

[0063] Binder yield 60%

[0064] Delamination strength (EN 1607) 13.4 kPa (TerraenbattsIndustri)—Aged 3.6 kPa (70° C./95%RH)

[0065] Tensile strength 5.5 kPa (Flexi A Batts)

[0066] Formulation 23

[0067] Resin

[0068] 24 kg DEA was transferred to a 80 l reactor and heated to 60° C.and stirred.

[0069] 6.7 kg ADP was added and the mixture heated and reacted at 130°C. for 60.minutes.

[0070] Thereafter cooled to 85° C. and 6.9 kg of THPA was added.Thereafter 16.9 kg PTA was added and the temperature raised to 130° C.for 120 minutes.

[0071] Subsequently the reaction mixture was cooled to 110° C. and 20.5kg water added. The temperature stabilised at approx. 50° C.

[0072] The mixture was stirred for further 15 minutes until homogenous.

[0073] The resin was cooled and transferred to a storage tank.

[0074] The resin solids content of 63.4% was determined at 200° C. Restmonomers: 37% of added DEA, 14% of added THPA, 25% of added PTA. Averagemolweight about 600.

[0075] The amount of rest monomers was determined by taking out seperatesamples of the resin for determination of each component. The sampleswere heated to 200° C. in order to remove all water, and then measured.

[0076] Before use 4% DEA and 25% solids Acumer 1510 calculated on resinsolids, 0.4% of sum solids silane and water to 25% solids content, wasadded and analysed.

[0077] Results of Trial

[0078] Binder yield 70%

[0079] Delamination strength (EN 1607) 12.1 kPa (TerraenbattsIndustri)—Aged 4.3 kPa (70° C./95% RH)

[0080] A number of these formulations were investigated for molecularweight and curing time at 250° C., the results being as follows:

[0081] Molecular Weight Analysis of the Polymeric Part or Moiety

[0082] Formulation:

[0083] 1) DEA:THPA—water added from start—average Mw 400-maximum 600

[0084] 3) DEA:THPA—water added at the end—average Mw 850-maximum 2000

[0085] 4) DEA:THPA:TMA—water added from start—average Mw 400-maximum 600

[0086] 5) DEA:THPA:TMA—water added from the start—average Mw 500-maximum1500

[0087] 9) DEA:THPA:TMA—water added with TMA—average Mw 500-maximum 1500

[0088] 20.3 kg DEA is heated to 60° C., whereafter 17.7 kg THPA is addedduring stirring. The temperature is raised to 95° C. and reactioncontinued for 1 hour, whereafter 25.8 kg water and 11.2 kg TMA are addedand right after 11.2 kg TMA is added. Temperature is held at 95° C. for½ hour before the reaction is stopped by cooling to room temperature.

[0089] Composition of resin:

[0090] 15% DEA monomer

[0091] 10% THPA monomer reacted to acid

[0092] 5% TMA monomer reacted to acid

[0093] 40% Water

[0094] Rest 30% is polymer of DEA:THPA:TMA

[0095] 16) DEA:THPA:SCA—water at the end—average Mw 550-maximum 1100

[0096] Curing Time at 250° C.

[0097] DEA:THPA:TMA or PTA—curing time about 2 minutes, formulation 9)and 12), table 1;

[0098] DEA:THPA:SCA—curing time about 1 minute, formulation 16), table1;

[0099] DEA:THPA:TMA or PTA added 20% polyacrylic acid—curing time 25-40seconds, formulation 9) and 12), table 1;

[0100] DEA:THPA:SCA added 20% polyacrylic acid—curing time 20 seconds,formulation 16), table 1.

[0101] The curing time was measured by preheating a droplet of binderplaced on a thin glass plate during 45 minutes at 90° C. after which itwas heated to 250° C. by placing the glass plate on a heating plate andstirred with a thin needle. The time until the binder droplet was curedwas measured after placing on said heating plate. The test method wasrepeated. Two more droplets of the same binder were tested using thesame method.

[0102] Factory trials utilizing the binder according to the presentinvention on a mineral wool Marine Slab 100 was carried out as follows.

[0103] Binder formulations were made based on selected resins to which20% w/w polyacrylic acid was added as a cross-linking agent and 0.2% w/wsilane as a coupling agent was added. Curing was carried out at 250° C.

[0104] The delaminating strength was measured according to EN 1607,whereby ageing is defined as remaining delaminating strength aftertreatment 15 minutes in an autoclave with 120° C. (1 ato).

[0105] Results

[0106] Formulation 16, DEA:THPA:SCA—water at the end.

[0107] Delamination strength 9 kPa—remaining strength after ageing25%—binder yield 75%

[0108] Binder distribution top-bottom is OK

[0109] Formulation 9, DEA:THPA:TMA—water added during TMA addition.

[0110] Delaminating strength 10 kPa—remaining strength after ageing68%—binder yield 80%

[0111] Binder distribution top-bottom is OK

[0112] Formulation 13, DEA:THPA:PTA—water at the end.

[0113] Delaminating strength 10 kPa—remaining strength after ageing52%—binder yield 65%

[0114] Less binder in bottom than top

[0115] Reference formulation 1 DEA:THPA—water added from start.

[0116] Delamination strength 7 kPa—remaining strength after ageing40%—binder yield <50%

[0117] Almost no binder in the ⅓ bottom part which is cut away beforedelamination measurements.

EXAMPLE

[0118] Reaction Temperature at 130° C. Compared with 95° C. (see Table2)

[0119] Formulation 9) reaction temperature 95° C.

[0120] Molratio DEA:THPA:TMA=1:0.6:0.3, coupling agent 0.4% VS 142 ofbinder solids.

[0121] Rest monomers: 55% of added DEA, rest monomers 40% of addedanhydrides.

[0122] Average molecular weight of oligomers 500.

[0123] Evaporation loss of binder solids in factory trial 25-30%

[0124] Product quality:

[0125] Delamination strength (EN 1607) 10 kPa, remaining strength afterageing 6.8 kPa

[0126] Product quality when using phosphonic acid as curing accelerator

[0127] Delaminating strength (EN 1607) 12.9 kPa, remaining strengthafter ageing 7.6 kPa.

[0128] Formulations 17-20 reaction temperature 130° C.

[0129] Molratio as formulation 9) DEA:THPA:TMA =1:0.6:0.3 90 kg DEA washeated to 60° C. whereafter 40 kg THPA was added during stirring. Thetemperature was raised to 95° C. whereafter the exothermic reactioncontinued to raise the temperature to 115° C. A Further 38.5 kg THPA wasadded and the temperature allowed to rise to 130° C. and maintained for10 minutes before 49.6 kg TMA was added. The temperature was held at130° C. for 60 minutes and then cooled to approximately 50° C. by theaddition of 120 l of water. The reaction mixture was kept at thistemperature for 60 minutes until all TMA was dissolved.

[0130] Rest monomers: 39% DEA of added, rest monomer 18% of addedanhydrides.

[0131] Average molecular weight of oligomers 600.

[0132] Before further dilution with water a base is added until a pH ofabout 6-8, preferably 7 results. The base may be an alkalihydroxide,amine or ammoniumhydroxide.

[0133] In these formulations ammoniumhydroxide was used.

[0134] Evaporation loss of binder solids was between 15 and 17%.

[0135] Before use an accelerator/crosslinker, a silane and water wasadded to 25% solids content.

[0136] Product quality when using 3% of solids phosphonic acid as curingaccelerator (formulation 17)

[0137] Delaminating strength (EN 1607) 15.2 kPa, remaining strengthafter ageing 9.1 kPa.

[0138] Product quality when using PAA as curing agent (Rohm and HaasAcumer 1510), (formulation 20).

[0139] Delamination strength (EN 1607) 11.2 kPa, remaining strengthafter ageing 4.5 kPa.

[0140] High silane addition as described in the example above.

[0141] Silane Results

[0142] The binder mixture in formulation 17 was used for testingdifferent amounts of silane addition.

[0143] The binding strength was performed according to the grit bartest.

[0144] Preparation and Testing of Selected Binder Samples to Evaluatethe Binding Strength Towards Shots with Mineral Fibre Composition (GritBar Test)

[0145] Shots with size between 0.25 and 0.5 mm diameter were used tomake bars with dimensions 140 mm×25 mm×10 mm.

[0146] For making the bars 90 ml binder solution with 15% solids contentand from 0.2%-3.0% silane coupling agent of binder solids were mixedwith 450 g shots.

[0147] The coupling agent was gamma-aminopropyltriethoxysilane.

[0148] To some of the binder solutions were added NaH₂PO₂—H₂O (3% ofbinder solids) as curing accelerator.

[0149] Out of the 450 g shots mixed with binder solution can be made 8bars which is cured 2 hours at 200° C. in an incubator.

[0150] Four of the bars were broken directly (dry strength), the other 4are placed 3 hours in 80° C. water before they are broken (wetstrength).

[0151] The binding strength was determined by breaking the bars in ameasuring device, where the clamping length is 100 mm and the velocityof the compressing beam was 10 mm/min. Using the clamping length, widthand thickness of the bars, the bending strength was determined in N/mm².

[0152] Grit bar test results: Bending strength Dry N/mm² Wet N/mm² 0.2%silane 9 4 0.4% silane 9 4 0.6% silane 9 5 1.0% silane 9 7 1.2% silane 98 3.0% silane 9 8

[0153] A resin made according to formulation 22 with a mole ratioDEA:ADP=1:0.5, reaction temperature 130° C. was mixed with 25% Acumer1510 solids of resin solids and further added different amounts ofsilane VS 142.

[0154] Grit bar tests show: Bending strength Dry N/mm² Wet N/mm² 0.2%silane 9 3 0.4% silane 9 3.5 0.6% silane 9 5 1.0% silane 9 7 1.2% silane9 8 3.0% silane 9 8

[0155] The aged (wet) strength is improved by adding higher amounts ofsilane. (Silan VS 142 as a % of the sum solids)

[0156] Conclusions Based on Results:

[0157] Water addition at the end yielded less unreacted startingmonomers, whereby water addition at the end or together with the secondanhydride gives higher yield of amides in the resin. See table 1.

[0158] SCA as second anhydride yielded short curing time and high yieldof amides in the reaction product.

[0159] When the amount amides in the reaction product is too high (>40%of the DEA added) the delamination strength after ageing of the mineralwool products proved to be poor.

[0160] The preferable mol.ratio DEA to anhydride proved to be 1:0.9-1.2,whereby higher ratios of anhydrides may provide less water solubleresin.

[0161] Water should be added at the end, immediately before, or togetherwith the second anhydride.

[0162] The first anhydride is preferably THPA, mol.ratio 0.5 to 1related to DEA.

[0163] The preferred second anhydride is TMA or PTA.

[0164] SCA as second anhydride yielded good strength before ageing, butpoor ageing stability.

[0165] An example of a preferred resin consists of 30% polymer of DEA,THPA and TMA, 15% DEA monomer, 10% THPA monomer reacted with water todiacid, 5% TMA monomer reacted with water to triacid 40% water.

[0166] An example of another preferable resin consists of about 40% ormore polymer of DEA, THPA and TMA, about 10% or less DEA monomer, about10% or less THPA monomer and TMA monomer reacted with water to diacid,triacid respectively and about 40% water.

[0167] In the polymer about 50% of the DEA which has reacted to apolymer is preferably an amide and the other 50% has preferably reactedto an ester.

[0168] The invention is not limited to the above description but israther determined by the following claims.

1. Process for providing a binder for mineral fibers, comprising thesteps of: mixing together under reactive conditions an amine and ananhydride whereby water is added thereto, once substantially all theanhydride is dissolved in and/or reacted with the amine.
 2. Processaccording to claim 1 wherein a second anhydride is added to the reactionmixture.
 3. Process according to claims 1 or 2 wherein the water isadded to the reaction mixture when the first anhydride has reacted,immediately before or together with the second anhydride, or whensubstantially all the second anhydride is dissolved in the mixture ofthe first anhydride and the amine.
 4. Process according to any of thepreceding claims wherein water is added in an amount to make thereaction mixture easily pumpable at room temperature.
 5. Processaccording to any of the preceding claims wherein the amine is heatedfirstly to a temperature of at least 40, preferably at least 50 and mostpreferably to about 60° C., whereafter the first anhydride is added, andthe reaction temperature raised to at least about 70, preferably atleast about 95, and most preferably to at least about 120° C.
 6. Processaccording to claim 5 wherein the reaction temperature is raised to atleast about 90°, for example about at least 100°, preferably at least120°, and more preferably about 130° C., and is below about 200°,preferably below about 170°, and more preferably below about 150° C. 7.Process according to claims 5 or 6 wherein the second anhydride is addedto the reaction mixture when substantially all the first anhydride isdissolved.
 8. Process according to any of the preceding claims whereinthe first anhydride is an aliphatic anhydride.
 9. Process according toany of the claims 2-8 wherein the second anhydride is an aromaticanhydride.
 10. Process according to any of the preceding claims, whereinthe first aliphatic anhydride is selected from the group comprisingtetrahydrophthalic anhydride, and/or hexahydrophthalic anhydride,methyltetrahydrophthalic anhydride, succinic anhydride, nadic anhydride,maleic anhydride, glutaric anhydride.
 11. Process according to any ofthe preceding claims 2-10 wherein the second aromatic anhydride isselected from the group comprising phthalic anhydride, trimelliticanhydride, pyromellitic di-anhydride and methylphthalic anhydride. 12.Process according to any of the preceding claims wherein the amine,being a N-substituted beta hydroxy alkylamine, is selected from thegroup Di-ethanolamine, 1-(m)ethyldiethanolamine, n-butyl-diethanolamine,1-(m)ethylisopropanolamine, 3-amino-1,2-propanediol,2-amino-1,3-propanediol, tris(hydroxymethyl)aminomethane, mostpreferably diethanolamine.
 13. Process according to any of the precedingclaims comprising the further step of addition of one or more of thefollowing additives: an accelerator in order to accelerate curing speedand one or more resin additives such as aminosiloxane to improveadhesion to fibre surface, thermal and UV stabilizers, surface activecompounds, fillers such as clay, silicates, magnesium sulfate andpigments such as titanium oxide, hydrophobizing agents such as fluorinecompounds, oils, preferably mineral and silicone oils and one or morecorrosion inhibitors.
 14. Process according to claim 13, wherein theaccelerator is selected from the group comprising the acid orcorresponding salts of phosphorous acid, phosphoric acid, phosphonicacid, phosphinic acid, citric acid, adipic acid andβ-hydroxyalkylamides.
 15. Process according to claim 14 wherein thephosphinic acid has the chemical abstracts number 6303-12-5-83-PO2. 16.Process according to claims 13 or 14, wherein the additives are selectedfrom the group comprising mono-, di-, and polysaccharides, such assucrose, glucose syrup, modified starch, starch, urea, dicyandiamide,polyglycols, acrylics, furfural, carboxymethyl cellulose and cellulose,and polyvinyl alcohol, melamin.
 17. Process according to any of thepreceding claims, further comprising addition of a cross-linking agent,wherein the cross-linking agent preferably comprises a carboxylic acidgroup containing polymer, preferably in the form of polyacrylic acids orpolymethacrylic acids.
 18. Process according to claim 17 wherein thepolycarboxylic acid cross-linking agents are added to the reactionmixture, to be present in the weight percentage range of 5-25 and mostpreferably being about 20 wt. %.
 19. Process according to any of thepreceding claims further comprising addition of corrosion inhibitors.20. Process according to any of the preceding claims, wherein the moleratio of the amine to the first anhydride lies in the range of1.0:0.1-2.0, preferably 1.0:0.5-1.5, and most preferably 1.0:0.5-1.0.21. Process according to claim 20 wherein the amine is diethanolamine,and wherein the first anhydride is tetrahydrophthalic anhydride, and,being present in the mixture at a molar ratio of 1 to 0.5 respectively.22. Process according to claim 21, wherein the second anhydride istrimellitic anhydride or phthalic anhydride, wherein the secondanhydride is present in the mixture at a lower mole ratio than the firstanhydride, preferably being present in about half the amount of thefirst anhydride.
 23. Process according to any of the preceding claims,wherein a base is subsequently added to the reaction mixture, followingthe water addition.
 24. Process according to claim 23 wherein the baseis selected from the group comprising NH₃, diethanol amine (DEA),triethanolamine (TEA), alkalihydroxides, optionally mixed with apolyacrylic acid, preferably Acumer 1510 Rohm and Haas, Mw. about60,000.
 25. Process according to claim 23 or 24 wherein the base in theresin reaction mixture adjusts the pH upto about 8, preferably to lie ina range of about 6 to about 8 and most preferably adjusts the pH toabout
 7. 26. Process according to any of the preceding claims wherein anacid is added, preferably before addition of the anhydride and whereinthe acid is selected from the group comprising: adipic acid, citricacid, trimellitic acid, sebacic acid, azelaic acid and succinic acid,and is preferably adipic acid.
 27. Process according to any of theclaims 23-26, wherein the weight % of the polyacrylic acid in themixture lies in the range upto 50%, for example 30%, preferably 25% andmost preferably upto 20%.
 28. Process according to any of the precedingclaims further comprising the step of adding a silane, preferably in therange of 0.1%-5%, more preferably 0.2%-3% and most preferably about 1%by weight of the resin reaction mixture, preferably by weight of theresin solids, whereby the silane is most preferably prehydrolysedgamma-aminoprbpyltriethoxysilane (VS 142/Vitco).
 29. Binder for mineralfibers, obtainable according to any of the preceding claims 1-28. 30.Binder comprising the reaction product of an amine, a first anhydride, asecond anhydride and water and the polymeric part of the binder having amolecular weight of a maximum of about 2000 and preferably having anaverage molecular weight lying in the range of 300-1500, preferably400-1000, and most preferably 500-900.
 31. Binder according to claim 30,wherein the first and second anhydrides are those as defined in claims8-11.
 32. Binder according to claims 30 or 31, wherein the amine isselected from those as defined in claim
 12. 33. Binder according to anyof the claims 30-32, further comprising a binder additive as defined inany of the claims 13-18.
 34. Binder according to any of the claims29-33, having a curing time at 250° C. of at the most about 2 minutes,and preferably lying in the range 15-55, for example 20-40 seconds. 35.Use of water to reduce emissions and improve the average molecularweight of a binder for mineral fibers, comprising an amine, a firstaliphatic anhydride and a second aromatic anhydride by addition of thewater to the reaction mixture once the first anhydride is dissolved inthe amine.